1. Field of the Invention
This invention generally relates to a table assembly including a table which may move in a desired direction, and, in particular, to an X-Y table assembly suitable for use in various smaller-sized machines and devices.
2. Description of the Prior Art
An X-Y table assembly is well known in the art. Typically, such an X-Y table assembly includes a base, an X table mounted on the base slidably in X direction and a Y table mounted on the X table slidably in Y direction, thereby allowing the Y table to move in any direction in a plane relative to the base.
A typical prior art X-Y table assembly is illustrated in FIGS. 12 through 14. As shown, the X-Y table assembly includes a base 30, an X table 34 located above the base 30, a first pair of linear motion guide units 31 interposed between the base 30 and the X table 34, a Y table 38 located above the X table 34, and a second pair of linear motion guide units 35 interposed between the X table 34 and the Y table 38. Each of the first pair of linear motion guide units 31 includes an elongated rail 32 fixedly mounted on the base 30 extending in the X direction and a slider 33 slidably mounted on the rail 32 and fixedly attached to the X table 34. A plurality of rolling members, such as balls or rollers, are disposed between the rail 32 and the slider 33 to provide a rolling contact therebetween. Thus, the X table 34 may move in either direction along the X direction relative to the base 30. Similarly, each of the second pair of linear motion guide units 35 includes an elongated rail 36 fixedly mounted on the top surface of the X table 34 extending in the Y direction, normal to the X direction, and a slider 37 slidably mounted on the rail 36 and fixedly attached to the Y table 38. A plurality of rolling members are also provided between the rail 36 and the slider 37 so as to provide rolling contact therebetween. As a result, the Y table 38 may move in either direction along the Y direction relative to the X table 34, so that, in effect, the Y table 38 may move in any direction in a plane relative to the base 30.
In this prior art X-Y table assembly, use is made of three plates for base 30 and X and Y tables 34 and 38 and two pairs of linear motion guide units 31 and 35 to construct an X-Y table assembly. In this case, however, since separate components are assembled to construct an X-Y table assembly, there is a limit in making the overall size smaller and the accuracy cannot be high. In addition, the manufacturing cost tends to be expensive because of involvement of various assembling steps.
Another typical prior art X-Y table assembly is illustrated in FIG. 15, and, as shown, it generally includes a base block 39, an intermediate block 40 and a top block 41. The base block 39 is formed with a pair of upward projections, and the intermediate block 40 is formed with a pair of downward projections, each associated with one of the upward projections of the base block 39. A linear motion guide unit 42 is interposed between the associated pair of upward and downward projections. The linear motion guide unit in this case may include a pair of oppositely located guide members, each having a V-shaped groove, and a plurality of rolling members, such as balls or rollers, interposed between the oppositely located guide members to thereby provide a rolling contact therebetween.
The intermediate block 40 is formed with a pair of upward projections and the top block 41 is foraged with a pair of downward projections, each associated with a corresponding one of the upward projections of the intermediate block 40. Similarly, a linear motion guide unit 42 is interposed between the associated pair of upward and downward projections of the intermediate and top blocks 40 and 41. In this case, each of the blocks 39-41 is fabricated by forging and cutting so that they are relatively large in size as well as in weight. Thus, the resulting X-Y table assembly is rather large in size and heavy in weight, though it may be suited for sustaining a relatively large load. There is apparently a limit in making this kind of X-Y table assembly smaller in size and light in weight.